This invention is an extension of the art taught in my U.S. Pat. No. 4,065,902, granted to me Jan. 3, 1978, and relates to further improvements in the same field and is extended to wood siding and flooring, including modifications to both the covering materials and the wood framing members to which they are attached. The problem with my prior invention is that the metal covered wood roofing planks had to be narrow in order that a single nail at one edge could properly fasten the planks to the roof framing. Wide roofing planks could not be adequately nailed and worst of all, such single edge nailing did not provide adequate resistance to shear forces, even when using narrow planks with more nailing.
Also in building construction, other similar problems are apparent that could be solved by an improved method of attaching siding, floor boards and roof boards in a manner where they are adequately attached, resist shear and have no face nailing. There is no use having water proof joints between metal covered roof planks if you are going to pierce the face of the metal by nailing. The same goes, to a lessor extent, to metal covered wood siding. However, metal covered siding, and even wood siding that is not metal covered, such as log siding, can have their appearance ruined by tradesmen who leave hammer marks when they nail. In the case of log siding, which is intended to appear as if the wall is solid logs, vertical rows of hammer marks and nail heads showing every two feet along the wall make it apparent, even to the novice, that it is only wood siding. Face nailing of wood outside decks spoils the deck's appearance and people often trip on spike heads that have worked up. When one observes old houses, it can be noted that hammer marks start face decay and that sweating of nail heads, and the nails themselves, cause rot around the nails to such an extent that sometimes the siding can be pulled off right over the nail heads and often the heads have been rusted off. Even if the nails are sheltered from the weather they cause deterioration in time. They pierce a hole through the siding, and water vapor from inside the house finds escape along the nail causing it to rust and the wood to deteriorate. My invention teaches how to fasten the cladding or facing material, i.e., the roof boards, the siding, the decking and the flooring to their respective rafters, studs and joists without face nailing. My answer is a means to lock the cladding to the rafters, studs or joists with a special dovetail joint. This system eliminates the need for plywood sheathing or braces to resist shear by locking the elements together, like an egg crate, which provides even greater shear resistance when wider planks are used. Both the cladding and the framing members have to be modified to obtain the locked on feature. The cross groove on the cladding has to be undercut on. its sides to form a locking dovetail means. The framing rafters, studs or joists have a similar dovetailed male end that is slit on its end to allow the sides of the male edge to be squeezed together to fit between the outer lips of the cross groove as the cladding is forced on it. The sides will snap back to their original configuration when the male edge of the framing is all the way in, locking the cladding permanently to the framing.
If the roofing planks, or the siding planks, are metal covered, the metal can be formed, as taught in my 1978 invention, to make their edge joints waterproof. Nails can be used, as taught in this invention, if they are hidden in the tongue and grooves. In the woodworking art, tradesmen have always been frustrated by the fact that when a plank is resawn into two boards, the boards will tend to cup on the resawn side. This happens because, no matter how dry we kiln dry the plank on its outside, the heart of the plank will always be wetter. When the plank is split into two boards, the wetter inside face will slowly air dry until it is the same moisture content as the outside. This causes the inside to shrink as it drys, cupping the board in accordance to the difference in dryness. This invention takes advantage of this, otherwise, unfortunate phenomena. Bevelled boards make the best siding, or roof boards. These are always made by diagonally sawing square planks into two bevelled boards. These boards will, in time, cup. If we cover the former outside of the boards with sheet metal, the cupping action will stretch the metal very tightly to the boards. This will allow the use of thinner metal and it will become almost a part of the board, like a very heavy coat of enamel, but will make the board stronger. Using thinner metal will lower the cost and, for instance, will bring the cost of a copper roof to a more affordable level. A new roofing product is born that can be permanently set to its rafters without visible nails, and is even lower cost because the need for plywood is eliminated, and if the roof is copper, it will endure for many decades. Similarly, thinner sheet metal, or aluminum, covering can be used on siding. If the metal has a baked on enamel finish, maintenance costs can be avoided for many decades.
Metal siding and roofing are often disliked because of their tinny sound when touched, or hit, by anything. Even wind makes it rattle and, in time, the sheets tend to work loose and allow the weather in. Hail is particularly noisy. When the metal is thin and stretched tight to the cladding, it does not rattle and even when thumped with the fist, it sounds like a solid timber, as no tinny or metallic sound is heard. The combination of wood and tight metal has a high quality feel and appearance, particularly when the roof is copper and the siding is aluminum with richly colored baked on enamel finish. Both last indefinitely. If the wood is, say, Douglas Fir, which has a hard surface, it will be very hard to dent or pierce the metal through misadventure. Perhaps, best of all, the metal covered siding, or roofing, is fire resistant.
The tendency for wood to cup when two pieces are sawn from a single piece can be turned to more useful purposes. Decking used outdoors can be designed so that its center is always bulged upwards so that it will shed water. Flat decking, or decking that naturally cups, will hold water, which soon leads to deterioration of the finish and to rot. Log siding is made from square boards, which means a lot of the wood is wasted to make the curve. If cupped pieces are used, then less wood needs to be wasted to get the curved log-like appearance, and can be made from thinner wood. Similarly, clam shell casing is curved and the backside is partly plowed out to arch the casing over rough spots and make the edges fit tightly. This wastes wood. Cupped pieces would involve less waste, and can be made from thinner pieces of wood.
Log house walls use a larger volume of wood than framed house walls. Costs are lowered by using tree stems that are green and that are processed no further than debarking and corner notching. However, the weight factor of wet timber reduces the radius of acceptable delivery costs and the logs shrink, settle and check in an unacceptable way. Dead tree stems cut the weight and shrinkage problem, but produce faults like rot and incipient rot and vermin.
It takes months in a kiln and many months in the air to dry freshly cut tree stems. Over the years and, in fact centuries, sawn, dried and planed squared timbers have, in many cases, taken over from round logs. High quality homes, built of cedar, redwood and white oak, as well as lower cost pine, spruce and fir, have appeared in Europe and North America, usually using 4" thick tongue and groove planed, kiln dried timbers.
In the U.S. and Canada, authorities are faulting these timber houses because 4" nominal, or 31/2" actual, wall has not enough insulation value. Simply making the walls thicker is just too expensive, especially with the richer quality woods. My invention envisions a wall built of two 2" planks locked to each side of the key like stud, previously disclosed. This produces a cavity to take insulation and hide electric wiring. It is an axiom that two 2" planks, good on one side, are considerably less costly than a 4" plank, good on both sides. They are so much easier to come by out of the tree, and 4" takes four weeks to kiln dry and 2" takes one week. The composite 2" plank and stud wall can be produced at comparable cost to the solid 4" wall. The cost of the wall can be further reduced by using lower cost pine planks on the inside (which are whiter and brighter) than, say, cedar or oak on the outside. In some rooms the inside planks can be left out all together, and very inexpensive gypsum drywall can be used attached directly to the studs. This cavity wall timber house can be built to look exactly like a 4" timber house. I have invented a Danish type notch corner finish, or a Russian style timber corner post can be used to complete the corner. The insulation factor can be raised from R-7 for 31/2" of timber wall, to R-26 for an 81/2" cavity timber wall (R-11 is required in most areas). No nails will show, and the 2" planks can be curved to simulate a log wall. Square studs that fit tightly between the inside and outside planks and nailed in with hidden nails, as is the siding, can be used to frame doors and windows; also corners and partition junctions, these usually cannot be placed exactly where key locked evenly spaced studs occur.